The steel fabrication process, step by step

1. Detailing and numbering

The detailer builds the 3D model (e.g. in Tekla Structures), adds connections and runs numbering: identical parts receive the same part mark and identical assemblies the same assembly mark. Drawings, NC files (DSTV) and DXF files are produced from the numbered model.

2. Material planning

The BOM is turned into a cutting plan (nesting of plates, bar lengths for sections) and a material requisition. Usable remnants go back to stock.

3. Part preparation

• Cutting: plates by laser, plasma or oxy-fuel; sections by band saw.
• Holing: drilling or punching from NC data; slots and copes.
• Forming: press-brake bending of plates and angles; roll-forming of purlins.

4. Assembly and welding

Parts are fitted and tack-welded to the main part (fit-up), checked dimensionally, then fully welded to a qualified welding procedure (WPS) by a qualified welder. Built-up I-sections are usually welded by submerged arc or MAG on an automatic line.

5. Inspection

Visual inspection of every weld; non-destructive testing (MT, UT…) at the rate required by the execution class; dimensional checks against the drawing. Defects lead to repair and re-inspection, recorded in a non-conformance report (NCR) when outside tolerance.

6. Surface treatment

Blast cleaning (e.g. to Sa 2½), then painting to the specified dry film thickness, or hot-dip galvanising. Coating is inspected before release.

7. Marking, packing and dispatch

Each piece receives its mark and label; pieces are bundled or packed into packages, loaded into containers or onto trucks with a packing list, and shipped with the quality dossier.